Sulfurized fatty oils

ABSTRACT

Sulfurization with elemental sulfur of a fatty mixture consisting essentially of about 80-95 weight percent prime burning lard oil and about 5-20 weight percent alkyl oleate yields a sulfur-containing oil-soluble product suitable for use as a substitute for sulfurized sperm oil additives for imparting extreme pressure properties to high aniline point mineral oil lubricants.

United States Patent Vienna et al.

[ Nov. 26, 1974 SULFURIZED FATTY OILS Inventors: Paul C. Vienna, CalumetCity;

Marvin J. Den Herder, Olympia Fields, both of I11.

Assignee: Standard Oil Company, Chicago, Ill.

Filed: Jan. 2, 1973 Appl. No.: 320,076

U.S. Cl. 252/48.6, 260/125 Int. Cl C10m l/38 Field of Search 252/486,125

References Cited UNITED STATES PATENTS 1 l/l939 Smith 252/486 3,740,3331/1973 Hutchinson et al 252/48.6

Primary Examiner-W. Cannon Attorney, Agent, or Firm-Edwin C. Lehner; A.G. Gilkes; William T. McClain [5 7] ABSTRACT 5 Claims, N0 DrawingsSULFURIZED FATTY OILS BACKGROUND OF THE INVENTION tion agents have beenextensively used as metalworking lubricants and especially as cuttingoils. In recent years, it has been found that the mineral oilcomponentof such lubricants contain constituents that may be toxic orcarcinogenic in nature and therefore undesirable due to the potentialharm that might occur when brought in contact with the human body. Ithas been found that the polycyclic aromatic constituents natu rallypresent in most mineral lubricating oils are the undesirableconstituents. Accordingly, it is necessary to remove these constituentsfrom the oil in order to have a mineral lubricating oil suitable for thepreparation of metalworking oils that are not harmful to the human body.The polycyclic aromatics are highly polar and can be removed by suitablesolvent extractionmethods well known to the art. Naturally occurringparaffmic or naphthenic petroleum oils or solvent extracted oils containless than about 10 percent carbon in aromatic bonding, as determined bythe n-d-M Method usedfon determining the hydrocarbon type analysis oflubricating oils, have been found to be relatively free of toxicity andcarcinogenicity characteristics. A description of the n-d-M Method maybe found on p. 226 of Physical Chemistry of Lubricating Oils by A.Bondi, Reinhold Publishing Corp, N.Y., 1951. Such oils containing minoramounts of the polar aromatic constituents are relatively poor solventsfor organic sulfur compounds. Such oils, which are highly refined oilshaving an aniline point of at least 190F, are now used as the princi palcomponent of commercial metalworking lubri cants.

Conventional sulfurized liquid triglycerides, such as the naturallyoccurring fatty oils of animal, vegetable, or mineral origin, arewell-known additives for use in the preparation of mineral oil-basedmetalworking lubricants. Due to the change of the mineral oil used asthe base for making compounded metalworking lubricams and the lack ofsolvency characteristics thereof, it is not possible to formsatisfactory oil blends of more than 2-3 percent of sulfurized fattyoils in mineral oil. In other words, the prior art sulfurized fatty oilsare substantially insoluble in the aforesaid mineral oilscontainingminor amounts of polar aromatic constituents. The use of the sulfurizedfatty oils are desirable for'im; parting additional lubricity to themineral oil metalworking fluids. V

Another well-known class of sulfurized fatty materials are thesulfurized unsaturated mono-estersof fatty acids as exemplified bymethyl oleate.

A widely used sulfurized fatty material is sulfurized sperm oil, for inaddition to good solubility, it provides good lubricity, anti-wearproperties, and resistance against thermal and oxidative resistance whenused as an additive in high aniline point mineral oils. Importation ofsperm oil is now prohibited. by the Federal government. Thus, areplacement product is required.

Sulfuri zed lard oil is not a suitable replacement because of its poorsolubility in high aniline point mineral oils and also poor thermal andoxidation stability. Methyloleatehas good solubility in high anilinepoint mineral oils but it has very poor thermal and oxidation stability.

SUMMARY OF THE INVENTION It has been discovered that; a mixtureconsisting essentially of about to about 95, preferably to 93, w ei ghtpercent prime burning lard oil and about 5 to about 20,preferably 7 to15, weight percent alkyl oleate can be sulfurized with elemental sulfurto form a sulfurized product containing from about 8 to about 12,preferably about 9-1 1, weight percent sulfur in the bo'undfform andless than about 0.3 weight percent free sulfur, having the attributes ofsulfurized sperm oil. The sulfurized. product. of this invention is asuitable replacement for sulfurized sperm oil for use as extremepressure additives in high aniline point mineral oils.

1 The term prime burning lard oil as used herein and in the claimsrefersto and means the prime burning lard oil ofcommerce It is highly refinedlard oil that has been caustic treated to remove free fatty acids,slimes and proteins normally present in commercial lard oil. Ittypically contains less than 1 percent free fatty acid, as oleic, has asaponification number of about 197 and an iodine number of about 69.

The tem1*alkyl oleate as used herein and in the claims refers to andmeans a mixture of alkyl esters of saturatedand unsaturated fatty acidshaving 14 to 18 carbons, said mixture containing at least 50 weightpercent unsaturated fatty acids with not more than 10 weight percent ofunsaturated fatty acids containing conjugated double bonds in theunsaturated fatty acid fraction, said alkyl group containing 1 to 3carbon atoms. A particularly suitable alkyl oleate is the methyl oleate;methyl oleate is obtained. by the alcoholysis treatment of lard oil withmethanol which is a wellknown ester interchange reaction. The purifiedmethyl ester mixture typically contains less than 1.5 percent free fattyacids, about 37 percent saturated fatty acids,

and about 58 percent unsaturated fatty acids which includes about 7percent linoleic acid. In addition, technical grade methyl oleateproduct typically contains about 7 percent of C1446 saturated fattyacids and about percent of C unsaturated fatty acids which include about6 percent of linoleic acid, is also suitable for use in this invention.

Sulfurization of the prime burning lard oil and methyl oleate mixturewith elemental sulfur is conducted in accordance with conventionalsulfurization procedures. Generally this comprises simply heating themixture with requisite amount of elemental. sulfur at a temperature ofabout 300400F for about 1-8 hours.

The aniline point (ASTM D-6-l l) measures the solubility"temperature ofaniline and the lubricating oil. The aniline point is, therefore, ameasure of solvency characteristics of the lubricant. The higher theaniline point, the poorerthe solvency of the lubricating oil.

DESCRIPTION OF PREFERRED EMBODIMENTS A series of sulfurized fattymaterials, identified as samples A-H and described below, were prepared.

Each of the materials contained 10 weight percent sulfur. The methyloleate used in Samples A, C, E, F, and H was the product derived byalcoholysis of lard oil and in Sample D it was the technical gradeproduct, as deof Samples A-C, G and H, were essentially the same. Thestick-slip numbers as measured by ASTM D-2877- 70 for these test oilswere essentially equivalent.

The compositions of this invention are suitable rescribed above. Forpurposes of brevity, the prime burn- 5 P e e Q Sulfufiled p rm for useas additives in ing lard oil will hereinafter be referred to as PBLO.lubheahhg 0115 f metal Worklhg P p deslred, Sample A: sulfurized mixtureof methyl oleate eh Improvement 9 tempereture sehlblhty can be and pobtained through the incorporation of about 0. l-2 per- Samplesulfurized PBLO. cent of an oil-soluble mono-alkyl phenols, such as non-Sample C; a physical mixture of 10% sulfurized 1O ylphenol nlubricatingoil blends containing the sulfumethyl oleate and 90%sulfurized PBLO' rizgd additi iesfof this lIlVBl'ltlOl'li In h ghpegformanpe Sample D: sulfurized mixture of 10% methyl oleate ushna f asgear gm 6 Way and 90% PBLO mist oils, rock drill oils and multipurposeoils, the properties of lubricatin oil blends containin the sulfurized Sg g ample E. sulfurized mixture of 20% methyl oleate and PBLO oilcompositions of this invention can be further en- S 0 hanced by theincorporation of small amounts of the ample F. sulfurized mixture of 50%methyl oleate H k 1k ldth. h h l b d d 50% PBLO we nown zinc ia y i ioposp ates u meant a an ditives without any noticeable antagonism in suchSampleG: sulfurized sperm oil. blemm sample H: sulfunzed methyl it is tobe understood that additive concentrates com- Each of the above sam,plesof s u lfunzed fatty, prising the sulfurized product can be formulatedwith als was tested for oxidation stability and solubility in a theadditives referred to above as we as other addi Fmllme pomt mmerallubnctmg 01] by dlssolvmg tives, such as silicone defoamer agents andtackiness 5 Welght Percent of l p m solvemextractved agentsconventionally used in the lubricating amount. SAE 10 mmeral lubrlcatmgO11 havlhg an ahlhhe P Comparative cutting oils using sulfurized spermoil and of The OXldahOh test used was e Aecel' the sulfurized productsof this invention showed equiverated Breakdown Test No. H-lSO of theAmerican Soalem performance ciety of Lubrication Engineers Standard forMachine Tool Fluid. In this test, 40 grams of test oil and steel Weclalm' Copper coupons.are plaqed an Open beaker 1. Asulfurized fatty oilcomposition consisting essenwhlgh then held wlthout agltatlon for 70hours at tially of a blend of (a) about 80 weight percent to about 215 Fm i P The dllute Color (ASTM D4500) of 95 weight percent prime burninglard oil and (b) about the test oils lS determined before and after theoxida- 5 weight percent to b t 20 ight percent alkyl oletlehfest' Celerof the pp Coupons at the end Ohthe ate sulfurized to contain about 8weight percent to test 15 determined y T el p V1511 about 12 weightpercent bound sulfur and not more examlhed. for deposlts- The e h y wasdeterthan 0.3 weight percent free sulfur, said alkyl oleate mmed y P g100 ml of the mlxture In an ASTM being a mixture of alkyl esters ofsaturated and unsatuinch centrifuge tube and stored at 35F for 48 hou atrated fatty acids having 14 to 18 carbons containing at which time thetube is visually examined for separation. least 50 weight percentunsaturated fatty acids with not The results of the aforesaid tests areset forth in the fol- 40 more than 10 weight percent of unsaturatedfatty acids lowing table: containing conjugated double bondsin theunsaturated OXlDATlON TEST SAMPLE M NO. BEFORE AFTER SLUDGE COPPER STEELSOLUBlLlTY A 2.0 i 3.5 None 3B4A No Deposit Bright & Clear B 2.5 4 None38 No Deposit Separation C 2.5 6 None 4A-4B No Deposit Separation D 2.54 None 3B-4A No Deposit Bright & Clear E 3 6.5 Trace 3B 4A No DepositBright 8L Clear F 6 5 8+ Heavy 4B Stain Bright & Clear v' Jh G 2.5 4None 3B-4A No i gosit Bright & Clear H 3.5 4 Heavy 4-C Stain Bright &Clear These data show that samples A, D and E, of this infatty acidfraction and said alkyl group having 1 to 3 vention are comparable toSample G, sulfurized sperm carbon atoms.

oil in solubility and thermal and oxidation stability. Sample C, aphysical mixture only of the separately sulfurized methyl oleate andPBLO shows such mixture does not have the requisite solubility contraSample A.

2. The composition of claim 1 wherein (b) is methyl oleate.

3. The composition of claim 2 wherein the amount of bound sulfur isabout 9 weight percent to about 11 It is therefore apparent thatco-sulfurization of a methyl weight percent.

4. The composition of claim 2 wherein (a) is about 85 weight percent toabout 93 weight percent, and (b) is about 7 weight percent to about 15weight percent.

' 5. The composition of claim 2 wherein (a) is about weight percent, (b)is about 20 weight percent, and

the amount of bound sulfur is about 10 weight percent. i l

1. A SULFURIZED FATTY OIL COMPOSITION CONSISTING ESSENTIALLY OF A BLENDOF (A) ABOUT 80 WEIGHT PERCENT TO ABOUT 95 WEIGHT PERCENT PRIME BURNINGLARD OIL AND (B) ABOUT 5 WEIGHT PERCENT TO ABOUT 20 WEIGHT PERCENT ALKYLOLEATE SULFURIZED TO CONTAIN ABOUT 8 WEIGHT PERCENT TO ABOUT 12 WEIGHTPERCENT BOUND SULFUR AND NOT MORE THAN 0.3 WEIGHT PERCENT FREE SULFUR,SAID ALKYL OLEATE BEING A MIXTURE OF ALKYL ESTERS OF SATURATED ANDUNSATURATED FATTY ACIDS HAVING 14 TO 18 CARBONS CONTAINING AT LEAST 50WEIGHT PERCENT UNSATURATED FATTY ACIDS WITH NOT MORE THAN 10 WEIGHTPERCENT OF UNSATURATED FATTY ACIDS CONTAINING CONJUGATED DUBLE BONDS INTHE UNSATURATED FATTY ACID FRACTION AND SAID ALKYL GROUP HAVING 1 TO 3CARBON ATOMS.
 2. The composition of claim 1 wherein (b) is methyloleate.
 3. The composition of claim 2 wherein the amount of bound sulfuris about 9 weight percent to about 11 weight percent.
 4. The compositionof claim 2 wherein (a) is about 85 weight percent to about 93 weightpercent, and (b) is about 7 weight percent to about 15 weight percent.5. The composition of claim 2 wherein (a) is about 80 weight percent,(b) is about 20 weight percent, and the amount of bound sulfur is about10 weight percent.